uasyncio.synchro: Add Lock example.

uasyncio.synchro/example_lock.py

@@ -0,0 +1,27 @@
+try:
+    import uasyncio.core as asyncio
+    from uasyncio.synchro import Lock
+except ImportError:
+    import asyncio
+    from asyncio import Lock
+
+
+def task(i, lock):
+    print(lock)
+    while 1:
+        yield from lock.acquire()
+        print("Acquired lock in task", i)
+        yield from asyncio.sleep(0.5)
+#        yield lock.release()
+        lock.release()
+
+
+loop = asyncio.get_event_loop()
+
+lock = Lock()
+
+loop.create_task(task(1, lock))
+loop.create_task(task(2, lock))
+loop.create_task(task(3, lock))
+
+loop.run_forever()